Our research objective is to continue the development of artificial lungs and artificial kidneys operating on the membrane separation principle. New materials developed to biomedical specifications are available for use, especially microporous materials, and further developments and modifications of these materials are possible. The program involves: a) theoretical studies for quantitative design of systems with enhanced convective transport, especially using coiled tubes to generate secondary flows, with corresponding in vitro tests; b) development and testing of an implantable artificial lung based on a multiple-branched coiled-tube system; c) surgical techniques to achieve a permanent, ventilated skin-lined cavity in the chest and lung implantation; d) physiological studies of the performance of implanted artificial lungs; e) development of continuous, on-line measurement of oxygen transfer rate from the gas phase of membrane lungs, with use in performance measurement, especially in long-term perfusion; f) in the artificial kidney field, a continued search for biochemical specificity, particularly through hybrid artificial organs with special reference to the artificial pancreas; g) combination of engineering (fluid dynamics) and hematological studies of thrombus formation in artificial organs, with investigation of agents which can be administered to control platelet adhesiveness in extracorporeal circuits. We envision that this program will lead to improvements in extracorporeal oxygenators, in control of thrombus formation, new, biochemically-specific forms of hemo-dialysis such as the implantable artificial pancreas, and that advances will be made towards an implantable artificial lung for permanent pulmonary assistance.